A standard false tooth is made by making a positive primary mold from the patient's mouth from which it is cast from wax a base corresponding to the part of the tooth that is to fit in the vacant space in the patient's mouth. On the top of this base the crown of the tooth must be modeled by the dental technician in a shape that will coact with the opposing tooth or teeth and that will look normal. The finished model is then used to make another mold, typically from plaster, and the tooth is then investment cast, usually of a porcelain material for best appearance.
Shaping the top part of the tooth is an extremely difficult procedure bordering on an artistic endeavor. It takes considerable practice to produce a usable crown by a procedure that is more akin to sculpture than dentistry. Thus a dental student must spend a very many hours painstakingly constructing teeth of wax to master the basic elements of the procedure.
It is known for example from U.S. Pat. Nos. 424,050 and 4,206,545 to make up a crown from a decorative porcelain side piece and from a metal cap, but the model for such a crown is apparently modeled in the standard manner. Similarly U.S. Pat. No. 4,778,386 describes a two-part crown, but gives no hint as to how to model it.